package java.util;

/**
 * An object that implements the Enumeration interface generates a series of elements, one at a
 * time. Successive calls to the <code>nextElement</code> method return successive elements of the
 * series.
 * <p>
 * For example, to print all elements of a <code>Vector&lt;E&gt;</code> <i>v</i>:
 *
 * <pre>
 * for (Enumeration&lt;E&gt; e = v.elements(); e.hasMoreElements();)
 * 	System.out.println(e.nextElement());
 * </pre>
 * <p>
 * Methods are provided to enumerate through the elements of a vector, the keys of a hashtable, and
 * the values in a hashtable. Enumerations are also used to specify the input streams to a
 * <code>SequenceInputStream</code>.
 * <p>
 * NOTE: The functionality of this interface is duplicated by the Iterator interface. In addition,
 * Iterator adds an optional remove operation, and has shorter method names. New implementations
 * should consider using Iterator in preference to Enumeration.
 *
 * @param <E>
 *        the type of the elements returned by this enumeration
 *
 * @see java.util.Iterator
 * @see java.util.Enumeration#nextElement()
 * @see java.util.Hashtable
 * @see java.util.Hashtable#elements()
 * @see java.util.Hashtable#keys()
 * @see java.util.Vector
 * @see java.util.Vector#elements()
 */
public interface Enumeration<E> {

    /**
     * Tests if this enumeration contains more elements.
     *
     * @return <code>true</code> if and only if this enumeration object contains at least one more
     *         element to provide; <code>false</code> otherwise.
     */
    boolean hasMoreElements();

    /**
     * Returns the next element of this enumeration if this enumeration object has at least one more
     * element to provide.
     *
     * @return the next element of this enumeration.
     * @exception NoSuchElementException
     *            if no more elements exist.
     */
    E nextElement();
}